The present invention relates to a gage and system for both internally and externally measuring tapered threads or tapered parts of a device to insure a precision shape. This gage utilizes three tapered cylindrical or grooved rolls, known as the tapered grooved rolls. Additionally, smooth tapered rolls or pin noses can be disposed around an axis at 120 degrees to form an inscribed circle. These measuring devices are of ground cylindrical or grooved shape with the form of the API or premium product that is to be measured. Two rolls or pin noses are secured to the body of the gage and a third is movable which enables the gage to be attached to the part to be measured.
The present invention is used in the manufacturing or inspection process for measuring inside and outside effective function fit of pitch diameters for tapered threaded tubing and casing connections. This invention is a significant improvement over known gages not only because it can measure both inside and outside parts, but because it can utilize interchangeable measuring means, a pin nose and two different types of tapered rolls to be more convenient than any other system.
In the oil and gas production industry, many downhole products, such as drill pipe, hangers, tubing, casing and premium tubing and casing products, line pipe, sucker rod and all other API connections threaded on the ends to connect each other together. Many of these threads are tapered.
Threaded taper connections must be precise in their constructions to be leak free, tough, strong, fatigue resistance and durable.
The American Petroleum Institute (API) has a specification for threading, gauging and thread inspection of components used in the oil and gas productions industry. This requires manufactures to have a complete set of hardened and ground steel ring and plug working gages. By design, a gage must be purchased for each internal and external connection. There are currently 70-100 API sizes that must be purchased. Hardened and ground working ring and plug gages are heavy and cumbersome as well as expensive to purchase. These ring and plug gages are designed to be threaded onto connections and after repeated use, wearout.
This specification sets forth a gage for measuring pitch for the different types and sizes of tubing and casing connections. Within this gage, stated pitch diameter distances from the end of the threaded connection to the point of the tapered threads can be measured.
The expense for Premium Threading Supply Companies readily becomes apparent when the limited and propriety nature of these special thread forms is factored into the cost to manufacture. These thread forms are of a much higher precision and tighter tolerance and higher cost than normal forms. Accordingly, these gages also can wear at higher rates than standard API thread forms, because of the highly abrasive materials that premium threads are experience. The number of special or premium gages reaches into many hundreds or sizes and thread forms.
Whereas, these premium manufactures, must maintain a large inventory of gages of various thread forms and diameters, also the initial purchase price and cost of maintaining these gages and for the shipping of these gages to many on-site locations. It becomes a necessity to use a functional, adjustable, affordable, reliable and portable gage system.
This Effective Diameter System offers the advantages of low initial cost, adaptable to many internal and external diameters. Can be used to measure many thread pitches for tubing, casings and drill pipe taper threaded connections, has low maintenance cost and is very portable.
Others have attempted to provide indicating gages using two-point contacts for taper threaded products. These alternative gages are deficient in that they are a crest form and not true pitch diameter gages. If the thread height of the thread form cut into this connection is on the low or high side of tolerance, a true indicated reading of pitch diameter is not forthcoming.
The indicated readings of these gages do not fall within a GRandR study with any high correlation of repeatability for any given connection.
Thus, it has long been a desire of manufactures and inspection companies to have a gage give an accurate indicated reading of a threaded connection""s effective pitch diameter acceptance.
Various patents have covered gages for measuring only the inside or outside of a test part, or only one measurement, such as taper of a test part have been used. Applicant notes, for example, U.S. Pat. No. 2,730,808 for a gage for an externally tapered test part has a circular cross section comprising a frame, taper gaging means carried by the frame, the taper gaging means having a smaller diameter which corresponds to the smaller dimension of the test part and a larger diameter end corresponding to the larger dimension of the test part, and a taper gaging means having a laterally extending slot into the gaging means, and limit means mounted upon the gage for movement through the slot into the taper gaging means.
U.S. Pat. No. 2,725,637 which is an attachment to a gage. It is a concentricity attachment for a gage comprising a rigid support, a lever mounted on the support intermediate the ends of the lever for pivotal movement and for axial movement, with a groove in the lever and a screw carried by the support engaging in the groove. Further, this gage attachment includes spring means to push the lever axially, means at one end of the lever for engaging that portion of the test part whose concentricity is to be determined, and an indicator engaging the lever adjacent its other end to indicate the pivotal movement of the lever.
U.S. Pat. No. 2,849,804 has a gage which has no mention of utility for pin nose measurement. Specifically, it claims a gage comprising a frame, a plurality of studs mounted upon the frame in spaced relation, means mounting at least one stud on the frame for movement towards and from another stud, a gaging roll rotatably mounted on each stud and having a center axis, at least one circumferential thread gaging ridge upon the periphery of each roll, and a flat setting surface carried by each gaging roll at a distance from the center axis of the gaging roll the same as the radius of the pitch diameter of the thread gaging ridge, wherein each flat setting surface extends at right angles to a line through the center axis of the gaging roll.
U.S. Pat. No. 3,217,419 is directed to a screw thread indicator gage, which does not have the ability to measure non-thread indicators. Specifically, this invention is a screw thread indicator gage comprising a pair of stationary gaging rolls and another gaging roll movable toward and away from the stationary rolls, an indicator responsive to movement of said movable roll from a basic setting, a probe disposed in a plane perpendicular to a line extending from the center to the center of the stationary rolls. This probe is movable in response to the algebraic sum of the extent of movement of the first movable roll and the deviation of a thread element from a basic setting. The invention does involves computing means responsive to movement of said movable roll and said probe for computing the deviation of said thread element. It is unlike the present invention.
U.S. Pat. No. 3,609,870, is directed to a radially movable gaging means. This invention is a gage having radially movable gaging means comprising a slide and a carrier secured thereto with the carrier carrying a gaging element. A projection or radial abutting means is carried by the slide or carrier and engages the other for positive radial retention of the carrier with respect to the slide. The projection or radial abutting may be adjustable. Lateral retention means is also provided between the slide and carrier. For gaging means with an arcuate gaging element, one or more additional means are provided for adjusting each gaging means in a lateral direction to bring the arcuate gaging element into arcuate alignment and in a planar direction for an accurate planar relationship between gaging elements. This device requires the use of two spring means for engaging the device to be measured, and has a different construction for the moveable assembly as compared to the present invention.
U.S. Pat. No. 5,182,862, is for a thread gage to measure tapered threads comprising an active block slidably engaged to a guide rail. A biasing means for biasing the active block to a neutral position is also provided. A fixed block is also engaged to the guide rail passing therethrough. An indicator for transducing movement of the active block along the guide rail is part of the invention with a further active arm with one end secrued to the active block. This block means is unlike the present invention.
U.S. Pat. No. 4,524,524, describes a system of measuring the inside or outside pitch diameter of a straight or tapered threaded product at a selected distance from the end of the product by setting a predetermined horizontal distance between an upper pivotable flat thread contact surface and a vertical bearing surface and between a lower pivotable flat thread contact surface and the vertical bearing surface. The horizontal distance being measured is in a vertical plane which is perpendicular to the bearing surface.
The present invention is a dimensional system for measuring inside and outside surfaces of an object. It comprises a gage base, which is preferably a flat plate, and at least three removable spindles attached to the gage base. Further, a moveable roll assembly is attached to the gage base. The invention further comprises at least one guide rod, at least one spindle guide block, and at least one linear bearing. The invention further includes at least one spring, at least one guide rail block, a plurality of measuring means attached to each of said removable spindles and spaced equidistantly around a central axis with each measuring means being spaced equidistantly from the other measuring means around the central axis. The measuring means are each removably attached to the moveable roll assembly. A lever is included in the invention for adjusting the movable roll assembly. The lever can compress the spring on said moveable roll assembly, allowing the gage""s measuring parts, which can be a threaded tapered roll, a smooth tapered roll or a pin nose, to engage with a test part. A housing is attached to the gage base protecting an indicator which is also attached to the gage base is used for indicating one or more measurements of a test object, such as pitch, lead, taper or combinations of these measurements, known as Effective Pitch Diameter.